1. Field
The exemplary embodiments generally relate to material handling systems and, more particularly, to transport and storage of items within the material handling system.
2. Brief Description of Related Developments
Multilevel storage and retrieval systems may be used in warehouses for the storage and retrieval of goods. Generally the transportation of goods into and out of the storage structure is done with lifts for transfer to a vehicle on a storage level, vehicles travelling up ramps to a predetermined storage level, or with vehicles that include lifts traveling along guide ways. Goods stored within the storage and retrieval system are generally stored in storage spaces on each storage level such that a transport vehicle disposed on that level has access to one level of storage spaces. Generally, the lifts that transfer items to and from the storage spaces carry the vehicles between different storage levels, are incorporated into the vehicles (such as with a gantry crane) or have a paternoster configuration where the lift payload shelves continually circulate around a frame at a predetermined rate.
Generally sequencing of items picked from storage is performed by the vehicles picking the items or by a dedicated sorter that sorts the items during an outbound flow after being transported by the gantry crane or paternoster lift. The sorting of outbound items in this manner may result in the lifts performing multiple lift strokes to pick the items needed for a load-out or additional sorting steps thereby decreasing throughput of the storage and retrieval system.
It would be advantageous to increase a rate of item transfer to and from the different storage levels within a storage and retrieval system where items of a load-out are sorted at a lift interface and picked with a common lift stroke and where an order of sorted items at the lift interface is matched to a load stream of a common load, lift interface and/or lift.